Fixed #18465 -- Set date formats correctly on Oracle

Correctly configure NLS_SESSION_PARAMETERS to format Date and DateTime
on Oracle backend.

Thanks to Josh Smeaton for report & patch.

django/db/backends/oracle/base.py

@@ -479,13 +479,19 @@ class DatabaseWrapper(BaseDatabaseWrapper):
                 del conn_params['use_returning_into']
             self.connection = Database.connect(conn_string, **conn_params)
             cursor = FormatStylePlaceholderCursor(self.connection)
+            # Set the territory first. The territory overrides NLS_DATE_FORMAT
+            # and NLS_TIMESTAMP_FORMAT to the territory default. When all of
+            # these are set in single statement it isn't clear what is supposed
+            # to happen.
+            cursor.execute("ALTER SESSION SET NLS_TERRITORY = 'AMERICA'")
             # Set oracle date to ansi date format.  This only needs to execute
             # once when we create a new connection. We also set the Territory
-            # to 'AMERICA' which forces Sunday to evaluate to a '1' in TO_CHAR().
-            cursor.execute("ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS'"
-                           " NLS_TIMESTAMP_FORMAT = 'YYYY-MM-DD HH24:MI:SS.FF'"
-                           " NLS_TERRITORY = 'AMERICA'"
-                           + (" TIME_ZONE = 'UTC'" if settings.USE_TZ else ''))
+            # to 'AMERICA' which forces Sunday to evaluate to a '1' in
+            # TO_CHAR().
+            cursor.execute(
+                "ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS'"
+                " NLS_TIMESTAMP_FORMAT = 'YYYY-MM-DD HH24:MI:SS.FF'"
+                + (" TIME_ZONE = 'UTC'" if settings.USE_TZ else ''))
 
             if 'operators' not in self.__dict__:
                 # Ticket #14149: Check whether our LIKE implementation will

tests/regressiontests/backends/tests.py

@@ -66,6 +66,18 @@ class OracleChecks(unittest.TestCase):
         self.assertEqual(connection.connection.encoding, "UTF-8")
         self.assertEqual(connection.connection.nencoding, "UTF-8")
 
+    @unittest.skipUnless(connection.vendor == 'oracle',
+                         "No need to check Oracle connection semantics")
+    def test_order_of_nls_parameters(self):
+        # an 'almost right' datetime should work with configured
+        # NLS parameters as per #18465.
+        c = connection.cursor()
+        query = "select 1 from dual where '1936-12-29 00:00' < sysdate"
+        # Test that the query succeeds without errors - pre #18465 this
+        # wasn't the case.
+        c.execute(query)
+        self.assertEqual(c.fetchone()[0], 1)
+
 class MySQLTests(TestCase):
     @unittest.skipUnless(connection.vendor == 'mysql',
                         "Test valid only for MySQL")